1. Field of the Invention
The present invention relates to a rear-wheel steering apparatus in a four-wheel steering system of wheeled vehicles, and more particularly to a rear-wheel steering apparatus of the type which includes an electric motor drivingly connected through a speed reduction gear train to an input member of a linkage mechanism for steering a set of dirigible rear road wheels and arranged to be activated under control of an electric control device for controlling a turn-angle of the rear road wheels.
2. Description of the Prior Art
Disclosed in Japanese Patent Laid-open Publication No. 1-301465 is a rear-wheel steering apparatus of this kind which includes a single electric motor arranged to drive a linkage mechanism for steering a set of dirigible rear-road wheels. In the rear-wheel steering apparatus, it is required that the single electric motor has a high performance capable of steering the rear road wheels under a heavy load in stationary steering operation and steering the same at a high speed during high speed travel of the vehicle. To provide such a high performance, the electric motor becomes large in size, and a large electric current is required for control of the electric motor. It is, therefore, required to provide an electric control device for control of the large electric current, resulting in increase of the manufacturing cost.